It's really easy: Install ADE with winetricks. Then start it and log in with your Adobe ID. Now you can Download files to your computer. They are now in your home directory in the Folder My Digital Editions. Just copy them from there to your eBook Reader. Done!
This requires you to register the ebook Reader with Adobe on another Computer. But starting in Wine version 1.3.37, it's possible to do that within wine as well. For this and more, please look into instructions the WineHQ ADE website, specifically modifying the Ebook reader's drive letter to be a floppy drive with winecfg.